Well tool and method for using same

ABSTRACT

A tool for use in a wall such as a gas or oil well which comprises spaced apart inner and outer cylinders and means for admitting fluid from the interior of the inner cylinder to the annulus between the inner and outer cylinders, a cylindrical means (overshot) carried by the inner cylinder to extend over the outside of an external pipe already existing in the wellbore and to seal and grip with the external pipe. A method for connecting a new section of pipe which carries the above tool to an existing, external section of pipe in the wellbore by stabbing the cylindrical means (overshot) over one end of the pipe in the wellbore, sealing the joint between the overshot and the external pipe, gripping the external pipe so that it cannot be removed from inside the overshot, and cementing around at least part of the exterior of the overshot whereby the new pipe above the tool is joined to the existing pipe below the tool in a rigid manner.

United States Patent [191 Bell et a1.

[ WELL TOOL AND METHOD FOR USING SAME [75] Inventors: Larry N. Bell; Charles R. Knowles,

both of Anchorage, Alaska; Frank M. Schuh, Dallas, Tex.

[73] Assignee: Atlantic Richfield Company, New

York, NY.

[22] Filed: Jan. 12, 1972 [21] Appl. No.: 217,362

[451 Aug. 14, 1973 Primary Examiner-Stephen .l. Novosad Attorney- Blucher S. Tharp, Roderick W. Mac- Donald et al.

[5 7] ABSTRACT A tool for use in a wall such as a gas or oil well which comprises spaced apart inner and outer cylinders and means for admitting fluid from the interior of the inner cylinder to the annulus between the inner and outer cylinders, a cylindrical means (overshot) carried by the inner cylinder to extend over the outside of an external pipe already existing in the wellbore and to seal and grip with the external pipe. A method for connecting a new section of pipe which carries the above tool to an existing, external section of pipe in the wellbore by stabbing the cylindrical means (overshot) over one end of the pipe in the wellbore, sealing the joint between the overshot and the external pipe, gripping the external pipe so that it cannot be removed from inside the overshot, and cementing around at least part of the exterior of the overshot whereby the new pipe above the tool is joined to the existing pipe below the tool in a rigid manner.

5 Claims, 2 Drawing Figures PRIOR ART Patented Aug. 14, 1973 FIG.

WELL TOOL AND METHOD FOR USING SAME BACKGROUND OF THE INVENTION Heretofore in certain situations it has been found necessary to remove an upper part of the casing, tubing or other pipe in a wellbore and to replace the removed part of the pipe with new pipe. The problem then becomes how best to join the new pipe to the existing pipe which remains in the wellbore.

Heretofore an overshot has been used which carried a packoff on its interior surface. The overshot was stabbed over the upper end of the existing pipe in the wellbore with the packoff unset. Cement was then passed from the interior of the new pipe past the packoff and out of the overshot to cement the new and existing pipe to the next outer member, e.g., outer casing or the wall of the wellbore. Thereafter, the packoff was set. The conventional length for the overshot was three to four feet so that to obtain good bonding between the new pipe and existing pipe, substantial amounts of cement were placed outside of the overshot, down along the existing pipe, and up along the new pipe. Thus, whether desired or not, cement had to be placed outside the pipes and the pipes could not be pressure or tension tested until after the cementing had taken place and the packoff set. Sometimes in such a situation heating up of the existing and new pipe by pumping hot oil or other fluid therethrough caused expansion of the pipe and separated the overshot from the existing pipe thereby ruining the seal at the joint between the overshot and the existing pipe.

SUMMARY OF THE INVENTION According to this invention there is provided a tool which will connect'to existing pipe in a wellbore in a sealed and gripping manner so that the connection can be pressure and tension tested before cementing and which provides sufficient contact area between the interior of the outer cylinder (wash pipe) of the tool and the exterior of the existing pipe so that a strong and lasting joint can be made without having to force cement over the existing or new pipe beyond the area covered by the tool. By a special gripping feature of the tool in conjunction with the cementing within the tool a much more rigid joint is made-between the new pipe and existing pipe so that heat-up of the pipes while producing hot fluid therethrough will not destroy the physical or sealing integrity of the joint.

The tool of this invention employs spaced apart inner and outer cylinders, the inner cylinder carrying an overshot and the outer cylinder being a wash pipe, means for admitting fluid from the interior of the inner cylinder to the annulus between the inner and outer cylinders, the wash pipe being of substantially greater length than the total length of the inner cylinder and overshot, the overshot being a cylindrical means which is spaced from the inner surface of the wash pipe and which is adapted to extend over the outside of an external pipe existing in the wellbore to seal and grip with that external pipe.

The method of this invention employs the tool above described in which the tool is carried by a new section of pipe to be installed in the wellbore in connection with an existing section of pipe already in the wellbore comprising stabbing the overshot of the tool over the outside of one end of the existing pipe, sealing the joint between the overshot and the existing pipe, gripping the existing pipe so that it cannot be removed from inside the overshot, and placing cement around at least part of the exterior of the overshot and within the wash pipe.

Accordingly, it is an object of this invention to provide a new and improved well tool. It is another object to provide a new and improved tool for joining the new section of pipe to existing pipe in a wellbore. It is another object to provide a new and improved cementing tool. It is another object to provide a new and improved method for connecting a new section of pipe to an existing section of pipe in a wellbore. It is another object to provide a new and improved method whereby pipes can be connected in a wellbore with the use of a minimum amount of cement along the exterior of the pipes.

Other aspects, objects and advantages of this invention will be apparent to those skilled in the art from this disclosure and the appended claims.

BRIEF DESCRIPTION OF THE DRAWING FIG. I shows a cross section of a prior art tool as employed in a wellbore.

FIG. 2 shows a cross section of the tool of this invention as employed in a wellbore.

DETAILED DESCRIPTION OF THE INVENTION More specifically, FIG. 1 shows a wellbore 1 in the earth 2, the wellbore having casing 3 therein. Casing 3 contains existing, external pipe 4, the upper portion of which has been removed and to which it is desired to attach a new section of pipe 5.

The connecting tool comprises an overshot 6 which is carried by shoulder 7 which is attached to pipe section 5 by any desired means such as welding, threaded coupling, and the like. The interior surface of overshot 6 contains a conventional packoff or packer means 7' which can be actuated by a conventional means well known in the art and therefore not shown. Actuation of packer 7' completely blocks annulus 8 between the exterior of existing pipe 4 and the interior of overshot 6 to thereby seal the interior of pipes 4 and 5 from the exterior annulus 9 which exists between the interior of casing 3 and the exterior of pipes 4 and 5. Overshot 6 is held by the derrick so as to be spaced a distance 10 above the top end of pipe 4.

In operation, after overshot 6 is stabbed over the upper end of existing pipe 4 with packoff 7 unset, cement is passed down the interior of pipe 5 through space 10 and annulus 8 as indicated by arrow 11 and out of the interior of overshot 6 over the external surfaces of both pipes 4 and 5 as indicated by arrows 12 and 13. Thus, substantial amounts of cement are passed up along the exterior of pipe 5 as indicated by arrow 12 and down along the exterior of pipe 4 as indicated by arrow 13. This is necessary because the conventional length for overshot 6 is three to four feet and in order to effect rigid binding of the two pipes 4 and 5 it is necessary for cement to extend a substantial length up along pipe 5 and down along pipe 4. This, of course, necessitates filling annulus 9 with cement for whatever length the cement extends along both pipes 4 and 5.

It can be seen that before cementing, the new assembly of pipes 4 and 5 can be neither pressure tested nor tension tested since there is nothing to hold the pipes together and since packoff 7 is as yet unset. After cementing, if it should happen that packoff 7' does not effect a good seal, for example, by being fouled by the cement passing thereby, it is too late to make any change because annulus 9 has already been filled by cement.

It can be seen from the prior art of FIG. 1 that pressure and tension testing of the assembly of pipes 4 and is not possible before cementing and that a substantial portion of annulus 9 has to be filled with cement in order to rigidly connect pipes 4 and 5 but this also rigidly cements these pipes to casing 3. Further, there is 1 still some risk that upon producing hot fluid through pipes 4 and S, the expansion of these pipes due to heating can cause pipes 4 and S to move apart thereby breaking the physical integrity of the joint and even destroying the seal achieved by setting packoff 7'.

FIG. 2 shows the tool of this invention in the same wellbore environment as that of FIG. 1. It should be understood that casing 3 need not be present in the welibore environment in which the tool of this invention is utilized. Rather, casing 3 could be completely eliminated so that there is no physical object between the exterior of pipes 4 and 5 and the face of wellbore 1. It should also be understood that pipes 4 and 5 can be any type of piping utilized in a wellbore be it tubing, casing, or otherwise.

In FIG. 2, pipe 4 represents existing external pipe already fixed in the wellbore such as by cementing and the like at a point (not shown) further down along the length of pipe 4, while pipe 5 is supported at the earth's surface by the drilling tower. The tool of this invention is lowered from the earths surface while connected to pipe 5 by means of conventional coupling 20. The tool comprises an outer cylinder 21 (wash pipe) and a spaced apart inner cylinder 22 which carries a means 24 for admitting fluid such as cement from the interior of pipe 5 to the annulus 23. Annulus 23 is defined by the inner surface of wash pipe 21 and the outer surface of inner cylinder 22 combined with that part of the outer surface of pipe 4 which extends into wash pipe 21. Fluid admitting means 24 can be a conventional cementing collar which is also known in the art as a DV cementing collar or stage cementing collar. By means not shown because they are conventional and well known in the art, cementing collar 24 can be made to open and close cementing ports 25 depending upon whether communication between the interior of pipe 5 and annulus 23 is desired or undesired.

Inner cylinder 22 has attached at its lower end a substantially radially extending shoulder or flange 26 which carries cylindrical means (overshot) 27. Overshot 27 carries on its internal surface an annular seal means 28 which contains a pluralityof O-ring sealing elements 29. Overshot 27 also carries a gripping means 30 which can be one or more conventional slips.

Wash pipe .21 and inner cylinder 22 are carried in a spaced apart relation by adapter 31 which is adapted by means of threads 32 to be joined by way of coupling to new pipe 5. For sake of clarity, new pipe 5 is referred to as an external pipe section whereas existing pipe 4 is referred to as external pipe.

It can be seen that at a first (upper in the case of FIG. 2) end of the wash pipe 21 and inner cylinder 22 there is adapter 31 and near this first end is collar 24. It can further be seen that overshot 27 is carried by inner cylinder 22 in annulus 23 but spaced from wash pipe 21 and on an end of inner cylinder 22 which is opposite to that of adapter 31. It can also be seen that both overshot 27 and wash pipe 21 extend away from this first end and therefore away from both adapter 31 and inner cylinder 22.

It should be observed that wash pipe 21 is of substantially greater length than overshot 27. This is to provide a substantial amount of contact area between the inner surface of wash pipe 21 and the exteriors of overshot 27 and inner cylinder 22 and that portion of pipe 4 which extends into wash pipe 21. Therefore, if cement is passed through the interior of pipe 5 through ports 25 into annulus 23 and only fills a portion or all of annulus 23, sufficient contact surface area is made between wash pipe 21 and pipe 4 to rigidly connect the two together thereby rigidly connecting pipe 5 to pipe 4. If desired, cement can extend out from the interior of wash pipe 21, but even if it extends down along pipe 4 it still is not necessary for the cement to extend up along new pipe 5 as required by the prior art.

Thus, in any situation substantial amounts of cement along at least new pipe 5 is eliminated by the use of this tool without eliminating its function and, in the right situations, such as where a device or existing cement or some other obstacle outside of pipe 4 allows it, only annulus 23 is filled with fresh connecting cement. In any event, by the use of this tool, the placement of cement in the annulus between wash pipe 21 and casing 3 and i in the annulus between new pipe 5 in casing 3 can be eliminated so that these parts are not rigidly cemented to the casing 3 and so that they can be removed at a later time if desired. This would not be so if cement were placed upward along new pipe 5 for a substantial distance as required by the prior art.

When the gripping means 30 are slips, one or more of the slips employed should have its teeth angled in a direction generally toward adapter 31 so that pipe 4 cannot be forced out of overshot 27 or overshot 27 pulled off of pipe 4. When this is achieved, the assembly of pipes 4 and S can be tension tested before cementing. Because of seal means 28 sealing joint 40 between the top end of pipe 4 and inner cylinder 22 and because ports 25 can be closed, the interior of pipes 4 and 5 can be sealed from annulus 23 and the assembly pressure tested before cementing. In this manner, if anything shows to be incorrect during pressure and tension testing, the error can be corrected before the irrevocable step of cementing is taken. Of course, other slips can be employed in overshot 27 whose teeth are angled downwardly toward the lower end of pipe 4 to act as stop means for the downward movement of the tool if desired.

If desired, the tool can be set down on the upper end of pipe 4 so that the lower end of inner cylinder 22 actually touches the upper edge of pipe 4 or the tool can be held by the rig derrick so that it is spaced just upwardly from the end of pipe 4 as is shown by joint 40 of FIG. 2.

EXAMPLE Apparatus substantially as that shown in FIG. 2 was employed in a wellbore wherein casing 3 was 20-inch casing and pipe 4 was 13 %-inch casing. A conventional stage cementing collar was employed for fluid admitting means 24. Overshot 27 was 14 i4 inches in diameter and about 4 feet long while wash pipe 21 was 16 inches in diameter and about feet long so that a substantial contact area for cement was provided between the internal surface of the IOO-foot long wash pipe 21 and that portion of the 13 %-inch pipe 4 that extended into wash pipe 21.

The tool was lowered until overshot 27 stabbed over the upper end of pipe 4 and was held by the rig derrick so that the lower end of inner cylinder 22 was spaced from the upper end of pipe 4 while seal 28 engaged pipe 4. Slips 30 had their teeth directed upwardly so as to bite into the outer surface of pipe 4 should the tool be raised upwardly or pipe 4 drawn downwardly. Ports 25 were closed and the assembly of pipes 4 and 5 tested under tension and pressure. These tests proved successful after which ports 25 were opened and conventional well cement passed downwardly through pipe 5 and out ports 25 to fill annulus 23 and to fill the remainder of the annulus between pipe 4 and casing 3 below wash pipe 21 which was not already filled with cement.

A rigid joint between pipes 4 and 5 was thereby effected which could not be broken by movement of either of pipes 4 or 5 away from the other and which was pressure tight even before cementing.

Reasonable variations and modifications are possible within the scope of this disclosure without departing from the spirit and scope of this invention.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

l. A well tool comprising spaced apart inner and outer cylinders, adapter means fixing said outer cylinder and said inner cylinder in said spaced apart relation, means for admitting fluid from the interior of said inner cylinder to the annulus between said inner and outer cylinder, said fluid admitting means being carried by and below said inner cylinder, and a cylindrical means carried by and below said fluid admitting means, said cylindrical means being spaced from said outer cylinder, said cylindrical means having its end furthest from said fluid admitting means so as to extend over the outside of an external pipe, said cylindrical means carrying means to seal and grip with said external pipe, said outer cylinder being of substantially greater length than the total length of said inner cylinder, fluid admitting means, and cylindrical means.

2. A well tool according to claim 1 wherein said fluid admitting means is a cementing collar in said inner cylinder, said cylindrical means is on the opposite side of said collar from said adapter means and extends away from said collar, and seal means and grip means carried interiorly of said cylindrical means to seal and grip, respectively, with an external pipe when passed into said cylindrical means.

3. A well tool according to claim 2 wherein said collar is near a first end of said outer cylinder, said adapter means is at said first end of said outer cylinder and carries means to be connected to an external pipe section, said cylindrical means extends into the annulus between said collar and said outer cylinder but is spaced inwardly from said outer cylinder, said grip means is slip means carried by said cylindrical means in the interior thereof and extending inwardly from said cylindrical means, at least one of said slip means having its teeth oriented so as to prevent an external pipe from being forced or pulled out of said cylindrical means once an end of the external pipe has entered said cylindrical means, and the majority of the length of said outer cylinder extends away from said first end and from said cylindrical means.

4. A well tool according to claim 1 wherein said cylindrical means is carried by said inner cylinder by way of a shoulder means which extends substantially later ally outwardly from said cylindrical means into the annulus between said inner and outer cylinders.

5. A method for connecting a new section of pipe to an existing section of pipe in a wellbore comprising stabbing an overshot over the outside of one end of said existing pipe, sealing the joint between said overshot and said existing pipe from the exterior of said overshot, gripping said existing pipe so that it cannot be removed from inside said overshot, placing an elongate wash pipe around said overshot, and placing cement at least between the inner surface of said wash pipe and the outer surfaces of said overshot and the portion of the existing pipe which is inside said wash pipe. 

1. A well tool comprising spaced apart inner and outer cylinders, adapter means fixing said outer cylinder and said inner cylinder in said spaced apart relation, means for admitting fluid from the interior of said inner cylinder to the annulus between said inner and outer cylinder, said fluid admitting means being carried by and below said inner cylinder, and a cylindrical means carried by and below said fluid admitting means, said cylindrical means being spaced from said outer cylinder, said cylindrical means having its end furthest from said fluid admitting means so as to extend over the outside of an external pipe, said cylindrical means carrying means to seal and grip with said external pipe, said outer cylinder being of substantially greater length than the total length of said inner cylinder, fluid admitting means, and cylindrical means.
 2. A well tool according to claim 1 wherein said fluid admitting means is a cementing collar in said inner cylinder, said cylindrical means is on the opposite side of said collar from said adapter means and extends away from said collar, and seal means and grip means carried interiorly of said cylindrical means to seal and grip, respectively, with an external pipe when passed into said cylindrical means.
 3. A well tool according to claim 2 wherein said collar is near a first end of said outer cylinder, said adapter means is at said first end of said outer cylinder and carries means to be connected to an external pipe section, said cylindrical means extends into the annulus between said collar and said outer cylinder but is spaced inwardly from said outer cylinder, said grip means is slip means carried by said cylindrical means in the interior thereof and extending inwardly from said cylindrical means, at least one of said slip means having its teeth oriented so as to prevent an external pipe from being forced or pulled out of said cylindrical means once an end of the external pipe has entered said cylindrical means, and the majority of the length of said outer cylinder extends away from said first end and from said cylindrical means.
 4. A well tool according to claim 1 wherein said cylindrical means is carried by said inner cylinder by way of a shoulder means which extends substantially laterally outwardly from said cylindrical means into the annulus between said inner and outer cylinders.
 5. A method for connecting a new section of pipe to an existing section of pipe in a wellbore comprising stabbing an overshot over the outside of one end of said existing pipe, sealing the joint between said overshot and said existing pipe from the exterior of said overshot, gripping said existing pipe so that it cannot be removed from inside said overshot, placing an elongate wash pipe around said overshot, and placing cement at least between the inner surface of said wash pipe and the outer surfaces of said overshot and the portion of the existing pipe which is inside said wash pipe. 